The skin provides a protective barrier against deleterious materials present in the environment. Since the skin has a large surface area and is readily accessible, it has been used as the site of therapeutic delivery. Administration to the skin avoids the difficulties of other routes of administration, for example, the acid environment of the stomach encountered when oral administration is used or the pain associated with piercing the skin in parenteral administration. Numerous examples of transcutaneous delivery systems are known in the art, for example, U.S. Pat. Nos. 7,201,919, 7,097,853, and 6,946,144 all disclose various compositions and devices for transcutaneous administration of agents. There remains a need in the art for methods and compositions to improve the uptake of therapeutic agents from the skin. This need and others are met by the present invention.